Switching to 12V? Size Your Solar & Batteries

Yes, and for most people it gets easier. A modern 12V compressor fridge uses roughly 20 to 140 amp-hours a day, depending on its size and how hot it is (use the calculator above for your model). Size your lithium batteries and roof solar to match, and the sun puts back what the fridge uses every day.

• No more hunting for level ground before you can run the fridge.
• No flame to blow out in the wind and no propane to babysit.
• Your propane lasts longer because it only goes to the furnace, water heater and stove.
• Your whole RV gets better off-grid. The same solar and batteries run your lights, water pump, fans, and phone and laptop charging.

RV manufacturers are moving to 12V compressor fridges. Lithium batteries and affordable solar made them practical, and they solve the biggest headaches of propane absorption fridges:

• Efficiency: an absorption fridge cools with heat from a flame or an electric element. On 12V, that heater pulls roughly 12 to 15 amps nonstop, which is why 3-way fridges only use 12V while you drive. A compressor fridge cycles on and off and uses a fraction of that.
• It has to be level: Dometic and Norcold generally call for staying within about 3° side to side and 6° front to back. Running off-level for long periods can permanently damage the cooling unit. Compressor fridges don't care. The Dometic CRX series runs at up to a 30° tilt.
• Slow to cool, weak in the heat: absorption fridges can take many hours to reach temperature and often lose ground on hot afternoons. A compressor fridge cools down quickly and holds temperature like your fridge at home.
• More parts that can fail: burner, igniter, flue, gas valve, heating elements, control boards, and a sealed cooling unit that usually can't be repaired, only replaced.
• Fire risk: absorption fridges run an open flame and a very hot boiler. Cooling-unit defects have led to large recalls. In 2008, for example, Norcold recalled nearly 265,000 refrigerators whose cooling units could leak and overheat. A 12V compressor fridge has no flame and no boiler.
• Outside vents: absorption fridges need roof and sidewall vents that let in heat, cold, drafts and bugs.

It's tempting, but a household fridge isn't built for life on the road:

• Vibration: every mile shakes the compressor, copper lines, shelves and door hinges. Home fridges are designed to sit still, so they often don't last long on the road.
• Warranty: many residential brands won't cover a fridge installed in an RV.
• Power: a home fridge runs on 120V AC. Off-grid, it needs a pure sine wave inverter running 24/7, and the inverter's own draw and conversion losses add to your battery drain. A 12V fridge runs straight from your batteries.
• Fit and weight: home fridges rarely match RV openings, often mean cutting cabinets, and can be too heavy or too big to get through the RV door.
• No travel features: RV fridges have door locks, secured shelves and bins, and mounting points to hold them in place while you drive.
• Service: many RV shops won't work on residential fridges, and many appliance techs won't work in an RV.

Not with the right setup. A DC-DC charger lets your alternator recharge your house batteries while you drive, so the fridge runs on miles as well as sunshine. On shore power or a generator, your converter or charger keeps everything topped up. Many models also run directly on 120V AC.

No, but they help a lot. You can safely use about 90% of a lithium battery's capacity, compared with about 50% of an AGM. That means a lithium bank can be about half the size and weight for the same runtime. Lithium also recharges faster from solar. If you switch to lithium, use a charge controller with a LiFePO4 profile: see our Lithium MPPT Charge Controllers.

Most 12V fridges have low-voltage protection that shuts the compressor off before the battery is damaged. A full, closed fridge stays cold for hours. Start the generator, drive, or plug in, and it picks right back up. Sizing your bank for 2 to 3 cloudy days, which the calculator does for you, makes this rare.

Often, yes. Many 12V models are built as direct replacements for common absorption sizes. Enter your opening in our RV Fridge Finder to see every fridge that fits. When you switch, have the propane line capped by a qualified technician, and follow the new fridge's instructions for the old vents.

You'll hear a quiet hum while the compressor runs, a lot like a home fridge. Absorption fridges are silent. Many 12V models have a night or quiet mode that lowers the compressor speed while you sleep.

A compressor fridge doesn't run all the time. It cycles on and off to hold temperature, so a fridge rated at 8 amps might average only 2 to 3 amps across a day. Multiplying the label amps by 24 hours can double or triple your estimate. Wherever the manufacturer publishes daily energy use, we use it. Otherwise we estimate from rated draw and typical run time, and the calculator tells you which one you're seeing.